Synthesis of spacer

C. D. Heidecke and T. K. Lindhorst, Iterative synthesis of spacered glycodendrons as oligomannoside mimetics and evaluation of their antiadhesive properties, Chem. Eur. J., 13 (2007) 9056-9067. 

Scheme 2. Synthesis of spacer units containing an ester (carboxylic acid) in the central bay-region...

Figure 3.122 Synthesis of spacer-free Janus bis-carbene complexes using triazole as the...

Mohan, H, Gemma, E, Ruda, K, Oscarson, S, Efficient synthesis of spacer-linked dimers of A-acetyllactosamine using microwave-assisted pyridinium triflate-promoted glycosylations with oxazoline donors, Synlett, 1255-1256, 2003. 

Oscarson et al. [75] performed easy and efBcient synthesis of spacer-linked dimers of N-acetyllactosamine from the corresponding oxazoline donor 97, by applying pyridinium triflate as promoter combined with microwave heating. Compared with the promoter pyridinium p-toluenesulfonate, previously proven to be more effective than other sulfonates [76], the triflate salt increased the yield of dimers 100 by more than 30%. Microwave irradiation reduced the reaction time... 

Fig. 8.5. Synthesis of spacer-separated difunctional reagents of ferrocene...

This way out also is the subject of numerous contributions in the literature reviewed [16, 33, 35]. The unique aim of all is the synthesis of spacers or handle molecules, inserted between the phenyl moieties of the cross-linked polystyrene thread and a reactive group, not only to attach protected amino acids suitable for peptide synthesis to the polymer, but to facihtate peptide cleavage without loss of protecting groups on side functions (see Fig. 16). 

Finally, a very recent work described the synthesis of spacer-linked neodisaccharides of L-daunosamine [84], In a glycosylation reaction on a monosilylated 1,4-butanediol the main product obtained was the monoglycosylated unprotected diol. This may suggest either a desilylation due to the acidic conditions or a higher reactivity of the silylated oxygen of the acceptor. 

Hydrosilation reactions have been one of the earlier techniques utilized in the preparation of siloxane containing block copolymers 22,23). A major application of this method has been in the synthesis of polysiloxane-poly(alkylene oxide) block copolymers 23), which find extensive applications as emulsifiers and stabilizers, especially in the urethane foam formulations 23-43). These types of reactions are conducted between silane (Si H) terminated siloxane oligomers and olefinically terminated poly-(alkylene oxide) oligomers. Consequently the resulting system contains (Si—C) linkages between different segments. Earlier developments in the field have been reviewed 22, 23,43> Recently hydrosilation reactions have been used effectively by Ringsdorf 255) and Finkelmann 256) for the synthesis of various novel thermoplastic liquid crystalline copolymers where siloxanes have been utilized as flexible spacers. Introduction of flexible siloxanes also improved the processibility of these materials. 

Warrener RN, Pitt IG, Butler DN (1983) The synthesis of new linear and angular systems useful as rigid rods and spacers in the design of molecules. J Chem Soc Chem Commun 1340-1341... 

Warrener RN, Abbenante G, Kennard CHL (1994) A tandem cycloaddition protocol for the controlled synthesis of [n]ladderanes new rods and spacers. J Am Chem Soc 116 3645-3646... 

The synthesis of the first polymer-supported chiral Mn-salen derivatives was reported independently by Sivaram171 and Minutolo.171-173 Different monomeric Jacobsen-type units, containing two polymerizable vinyl groups, were copolymerized with styrene and divinylbenzene to yield the corresponding cross-linked polymers as a monolithic compact block.174-176 The less mobile system (Figure 19) with no spacer between the aromatic ring and the polymer backbone is less enantioselective. 

First examples of complexes of a,cj-digold alkylidenes have been prepared in moderate yields from the corresponding di-Grignard reagents with 2 equiv. of (Ph3P)AuBr as colorless, crystalline products. The structure of the dinuclear compound with the -(CH2)4- spacer has been determined (Equation (3)).19 Preparative efforts oriented at the synthesis of the analogous ethane, propane, and hexane derivatives were unsuccessful. 

In this context, divalent presentation of this promising candidate has been investigated by the authors using the fixed cone conformation of calix[4]arene to allow introduction of the molecules onto the upper rim, and their projection into the same portion of space, thus mimicking, to some extent, a small portion of the natural cell-surface ganglioside. The synthesis of the divalent neoglycoconjugate was based on initial functionalization of the corresponding diacid with an aminated spacer and further introduction of squaric acid moieties. 

A. Patel and T. B. Lindhorst, Multivalent glycomimetics Synthesis of nonava-lent mannoside clusters with variation of spacer properties, Carbohydr. Res., 341 (2006) 1657-1668. 

S. Hana, T. Yoshida, and T. Uryu, Synthesis of a new polylysine-dendritic oligosaccharide with alkyl spacer having peptide linkage, Carbohydr. Polym., 69 (2007) 436 144. 

One of the key technologies used in combinatorial chemistry is solid-phase organic synthesis (SPOS) [2], originally developed by Merrifield in 1963 for the synthesis of peptides [3]. In SPOS, a molecule (scaffold) is attached to a solid support, for example a polymer resin (Fig. 7.1). In general, resins are insoluble base polymers with a linker molecule attached. Often, spacers are included to reduce steric hindrance by the bulk of the resin. Linkers, on the other hand, are functional moieties, which allow the attachment and cleavage of scaffolds under controlled conditions. Subsequent chemistry is then carried out on the molecule attached to the support until, at the end of the often multistep synthesis, the desired molecule is released from the support. 

The synthesis of some multiblock copolymers was attempted by successive polymerization using this iniferter technique. However, pure tri- or tetrablock copolymers free from homopolymers were not isolated by solvent extraction because no suitable solvent was found for the separation. In 1963, Merrifield reported a brilliant solid-phase peptide synthesis using a reagent attached to the polymer support. If a similar idea can be applied to the iniferter technique, pure block copolymer could be synthesized by radical polymerization. The DC group attached to a polystyrene gel (PSG) through a hydrolyzable ester spacer was prepared and used as a PSG photoiniferter (Eq. 53) [186] ... 

The synthesis of the macrocycles 43 (Scheme 9) is an example of repetitive, highly stereoselective Diels-Alder reaction between bis-dienes 41 and bis-dienophiles 42, containing all oxo or methano bridges syn to one another. The consecutive inter- and intramolecular Diels-Alder reactions only succeed at high pressure. Obviously, both reactions are accelerated by pressure. The macrocycles are of interest in supramolecular chemistry (host-guest chemistry) because of their well-defined cavities with different sizes depending on the arene spacer-units. 

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